Crystalline silicon solar cells are a kind of battery devices that convert solar energy into electric energy by the use of the photoelectric effect of semiconductor silicon. In a solar cell, the internal current is produced under illumination conditions, and the electric energy is output through the frontside electrode and the backside electrode. Therefore, it is very important for solar cell electrodes have an excellent stability.
Aging resistant backside silver pastes disclosed in the invention is mainly composed of a conductive phase, an organic material and an inorganic binder. The backside silver paste is printed onto silicon wafers, sintered, and then used as the backside electrodes of the solar cells, mainly playing a role in collecting electric currents. A solar cell module is formed by series welding the cell frontside cathodes and the backside electrodes. Therefore, the stability of the welded back electrode directly affects the service life of the solar cell assembly, and the aging resistance of the backside silver pastes is very important.
With the increasing demand for the quality of the pastes used in solar cells, the aging tests of backside electrodes have been widely adopted by solar cell manufacturers. At present, the content of silver in the backside silver paste used for back electrodes is decreasing year by year, which leads to an inadequate sintering compactness and a great attenuation in the after-aging welding strength. Based on the favorable compounding of silver powder, nanosized copper powder, glass powder and organic carrier in the formula, the present invention solves the problem of the after-aging welding strength attenuation which occurred when most of the commercial backside silver pastes are used in the backside electrodes.